Additives for fuel antioxidants and for lubricants

ABSTRACT

ADDITIVES TO LUBRICANTS AND FUEL ANTIOXIDANTS, CONSISTING OF OR CONTAINING ISOINDOLINE COMPOUNDS OF THE FORMULA   1-(R-OOC-C(-CN)=),3-(HN=)ISOINDOLINE   IN WHICH R STANDS FOR AN ALKYL, ISOALKYL OR ALKENYL RADICAL WITH 7 TO 20 CARBON ATOMS.

United States Patent 3,594,319 ADDITIVES FOR FUEL ANTIOXIDANTS AND FOR LUBRICANTS Heinrich Vollmann, Leverkusen, Heinrich Leister,

Cologne-Stammheim, and Walther Lohmar, Bergisch- Gladbach, Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany N0 Drawing. Filed Jan. 21, 1969, Ser. No. 792,788 Claims priority, application Germany, Jan. 29, 1968, P 16 44 897.8 Int. Cl. Cm 1/32; C101 N22 US. Cl. 25251.5A 6 Claims ABSTRACT OF THE DISCLOSURE Additives to lubricants and fuel antioxidants, consisting of or containing isoindoline compounds of the formula NH H NE in which R stands for an alkyl, isoalkyl or alkenyl radical with 7 to 20 carbon atoms.

The present invention relates to additives to lubricants and fuel antioxidants. More particularly it concerns additives to lubricants and fuel antioxidants consisting of or containing isoindoline compounds of the formula l iH (I) in which R stands for an alkyl, isoalkyl or alkenyl group with 7 to 20 carbon atoms, preferably with 8 to 20 carbon atoms.

These isoindoline compounds have proved to be outstandingly effective as additives to lubricants and fuel antioxidants.

The preferred compounds of the Formula I are those in which R denotes an alkyl group with 12 to 20 carbon atoms. Compounds of the Formula I in which R is an alkenyl group with 18 carbon atoms have an especially high synergistic elfect in fuel antioxidants.

As radicals should be mentioned for R for example: C C -alkyl radicals such as the decyl-, dodecyl, tetradecyl-, hexadecylor octadecyl radical; C C -isoalkyl radicals such as the 2,2-dimethyl-octyl-(l), 2,2-dimethyldodecyl-(B), 2,2- dimethyl-4-iso-butyl-heptyl-(4), 2,3-dimethyl dodecyl (3), 2,2-dibutyl-hexyl (l),3 methylheptadecyl-( 17), or the 2,6,10,14-tetramethyl-hexadecyl- (16) radical; C -c -alkenyl radicals such as the decenl)-yl-(4), 2,6 dimethyl-decen-(l)-yl-(8), 2,6-dimethyldodecen-(2)-yl-( 12), 4-methyl-pentadecen (l4)-yl-(l), octadecen-(9)-yl-(1) or the 2,6,10,14 tetramethyl hexadecen- (l4)-yl-(16) radical.

The isoindoline compounds to be used according to the invention are insoluble in water; some are crystalline compounds, some are viscous liquids. They can be obtained, for example, by condensing 1,3-diimino-isoindoline and suitable cyanoacetic esters in solvents as is described in Belgian Pat. 703,669. The compounds are ashfree and non-volatile and thus facilitate their incorporation with organic material. The compounds are readily Patented July 20, 1971 ICC soluble in solvents, such as e.g. N-methyl-pyrrolidone and it is therefore possible to prepare also highly concentrated solutions with a view to better dosage.

The amounts in which the isoindoline compounds of the Formula I have to be used in any given case can easily be established by preliminary experiments; for use as additives to lubricants, amounts of 0.0011.0 percent by weight, based on the weight of the lubricants, and for use as additives to fuel antioxidants, amounts of 3-l0 percent by weight, based on the weight of the antioxidants, have usually proved suflicient.

With the aid of the isoindoline compounds of the Formula I it is possible substantially to improve lubricants of various types, particularly in respect of their resistance to oxidative attacks. This is mainly true of lubricants prepared from mineral oils and of lubricants of synthetic origin. For example, turbine, hydraulic, transformator and other highly refined industrial oils, soaps and fats, lubricating fats, but also synthetic polymers such as polybutenes and the like are, very effectively stabilised against attacks by air and oxygen. Compounds of the Formula I are also suitable for stabilising fats and oils of animal or vegetable origin.

The additives to lubricants to be used according to the invention are compatible with the majority of other additives to lubricants, for example, with detergents, agents for improving the stability of the lubricating film, and agents for improving the solidification point and the viscosity.

It is of special advantage to add the isoindoline compounds together with diphenylamines serving as antiagers such as N-phenyl-N-isopropyl-p-phenylene-diamine or 4,4'-dimethylbenzyl-diphenylamine. A synergistic effect is thus achieved.

It is further possible with the aid of the isoindoline compounds of the Formula I substantially to improve the antioxidising eifect of commercial antioxidants of various types, for example, of phenolic antioxidants, such as 2,6-di-tert.-butyl-4-methyl-phenol, 2,4-dimethyl-6-tert.-butyl-phenol, 2,6-di-tert.-butyl-phenol, and, in particular, of p-phenylene-diamine antioxidants, such as N,N'-diisopropyl-p-phenylene-diamine, N,N'-di-sec.-butyl-p-phenylene-diamine, N-phenyl-N-isopropyl-p-phenylene-diamine, N-( 1,3-dimethyl-butyl N'-phenyl-p-phenylene-diamine.

It is remarkable that the isoindoline compounds to be used according to the invention are compatible with most other additives to fuels, for example, with agents for increasing the resistance to compression and to antiicing agents and agents against the formation of residues and vapour bubbles.

The surprisingly high effectiveness of the isoindoline compounds of the Formula I as additives to lubricants was established in the apparatus described by C. Kroger in the journal Erdol and Kohle, vol. 2 (1949), page 390. This apparatus consists of a reaction vessel with connected open-end mercury manometer.

The small flask of 12.5 ml. capacity is charged with 1 g. of mineral oil in which 0.001 g. of antioxidant have been dissolved, and with 0.1 g. of copper powder. The copper powder is added as oxidation activator. Before the manometer is connected, the air is driven out of the reaction vessel by means of oxygen and the flask is then placed on an oil bath at a constant temperature of C. i0.5 C. A shaking device keeps the content of the flask in motion so that the copper powder is Well dispersed in the oil sample mixed with the antioxidant, and the oil sample remains in good contact with the oxygen.

Due to the heating, the pressure in the apparatus rises very rapidly and reaches an excess pressure value of up to 190 mm. Hg after 3-4 minutes; it decreases again when the oxidation reaction starts. The maximum excess pressure value is set as zero. The decrease of pressure in the system caused by the consumption of oxygen by the system is measured at certain time intervals. The magnitude of the velocity of oxidation is characterised by the decrease of pressure in mm. I-Ig/min. The lower this quotient is, the more effective is the antioxidant.

As starting oil for the tests there was used a mineral oil with the following characteristics:

Density at 20 C: 0.897 g./ml.; neutralisation number: 0.06 mg. KOH/g. oil; aniline point: 89.5 C.; solidification point: -28 C.; viscosity at 20 C.: 205.0 cst.; ash after combustion: 0.005 percent by weight.

The following compounds were used as additives:

l-(cyanocarboxy-methylene)-3- Compounds B through I are isoindoline compounds of the present invention.

The test results obtained with various additives are assembled in Table 1::

TABLE I Velocity of oxidation. mm.

Example lip 111111.

1 Base oil A t 0. 813

2. lie. ml plus copper powder r v l. 755

3. Base ml pills copper powder plus 0.1 percent 1.150

by weight (A) 4 Base oil plus copper powder plus 0.1 percent 0.532

by weight (B).

5 Base 011 plus copper powder plus 0.1 percent 0. 561

by weight (C).

6 Base oil plus copper powder plus 0.1 percent 0.507

by weight (1)).

Base 011 plus copper powder plus 0.1 percent 0.556

by weight (E).

Base oil plus copper powder plus 0.1 percent 0. 550

by weight (I 9 Base oil plus copper powder plus 0.1 percent 0.400

by weight (G).

10 Base oil plus copper powder plus 0.1 percent 0.384

by weight (11).

11 Base 011 plus copper powder plus 0.1 percent 0.500

by weight (I).

The surprising synergistic efiFect of the isoindoline compounds of Formula I in fuel antioxidants was demonstrated in the bomb test for liquid fuels according to ASTM D 52555 respectively DIN 51,780. According to this test, a test vessel of glass which has a capacity of 150 m1. and was previously cleaned and dried at 150 C., is placed in a carefully cleaned VZA-steel bomb. The steel vessel is charged with 50:1 ml. gasoline in which the desired amount of the antioxidant has been dissolved. The glass vessel is covered with a glass lid. The V2A- steel bomb is then sealed gas-tight with a lid. "The lid of the steel bomb is fitted with a fine-control valve and a terminal which is connected via a capillary spiral to a recording manometer. The VZA-bomb is rinsed twice with oxygen at 7 atm. excess pressure in order to remove the air initially present. Oxygen is then again pressed in at 7.00 to 7.14 atm. excess pressure. The bomb thus charged is placed, without shaking it. in a water bath which has been heated to 100 C. and is kept brisky boiling. The

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4 content of the bomb is in communication with the recording manometer so that the course of the pressure as a function of time, i.e. the pressure-time curve, is graphically recorded.

The time in minutes which elapses from the start of the test to the detectable absorption of oxygen, i.e. the pressure drop, is stated as induction period at 100 C."; the point of pressure drop in the pressure-time curve is the point which is preceded by a decrease of pressure of exactly 0.14 kg./sq. cm. within 15 minutes and followed by a decrease of pressure of at least 0.14 kg./sq. cm. within 15 minutes.

The test results obtained with the various additives are assembled in the following Tables II and III: in Table II the protection against oxidation achieved by various addilives in thermally produced heavy cracked gasoline at 100 C.; in Table III, the protection against oxidation achieved by various additives in catalytically produced heavy cracked gasoline at 100 C.

The gasolines used for the tests had the following characteristics:

Thermally Catalytically produced produced heavy heavy cracked cracked gasoline gasoline Density at 20 (7., g./ml 0.848 0. 755 Bromine number. 24100 g 52 83 Diene content, percent by weight 8. 1 3. 3 Carbon, percent by weight 90. 6 86. 8 Hydrogen, percent by weight. 9. 4 13.4 Non-aromatic, percent by weight 19. 8 71. 49 Lower aromatics. percent by weight 74.8 21. 86 Higher aromatics, percent by weight. 5. -I 6.65 Uum before ageing. lug/100 rnl 56 1 Gum alter ageing, mg./100 ml 10. 400 2. 104

The additives used were:

1 (cyano carbooctadecene (9') yl (1') oxymethylene)-3-imino-isoindoline (A),

N-phenyl-N'-isopropyl-p-phenylene-diamine (B),

N (1,3 dimethylbutyl) N phenyl p phenylenediamine (C),

2,6-di-tert.butyl-4-methyl-phenol (D) and mixtures of A+B, A+C and A+D.

TABLE II ctongen- Inductiog ra Ion erlo Test Additive (p.p.m.) anin.)

10 2G 1 A 28 100 28 10 48 2 B 50 115 100 166 10 52 3 Mlxture of 1 part A plus 9 parts 13.... 147 230 TABLE III Congan- Induction tra on per 0d Additive (p.p.m.) (min.)

100 811. Mixture of 1 part A plus 9 parts 13. 100 925 I 100 772 Mixture of 1 part A plus 9 parts C. 100 980 100 460 9 Mlxture of 1 part A plus 9 parts D. 100 590 What is claimed is: 1. Additives for fuels and lubricants consisting essentially of isoindoline compounds of the formula in which R stands for an alkyl, isoalkyl or alkenyl radical with 7 to 20 carbon atoms.

2. Lubricant of improved oxidation stability com-prising a natural or synthetic lubricant and an isoindoline compound of the formula in which R stands for an alkyl, isoalkyl or alkenyl radical with 7 to 20 carbon atoms.

3. The lubricant of claim 2 comprising 0.00ll.0 percent by Weight of the isoindoline compound based on the weight of the lubricant.

4. Antioxidant mixture of increased effectiveness for liquid fuels comprising a phenolic antioxidant or a pphenylene-diamine antioxidant and an isoindoline compound of the formula in which R stands for an alkyl, isoalkyl or alkenyl radical with 7 to 20 carbon atoms.

5. The antioxidant of claim 4 comprising 3-10 percent by weight of the isoindoline compound based on the weight of the phenolic or p-phenylene-diamine antioxidant.

6. The antioxidant of claim 4 wherein the p-phenylenediamine antioxidant is a member selected from the group consisting of N,N'-diisopropyl-p-phenylene-diamine, N, N-disec.-butyl-p-phenylene-diarnine, N phenyl-N'-is0- propyl-p-phenylene-diamine, N (1,3 dimethylbutyl-N- phenyl-p-phenylene-diamine.

References Cited UNITED STATES PATENTS 2,521,415 9/1950 Schmerling 44-63 2,930,758 3/1960 Tierney et a1. 25250X 3,129,227 4/ 1964 VanVelzen 4463 3,322,785 5/1967 Fletcher 252403 DANIEL E. WYMAN, Primary Examiner W. J. SHINE, Assistant Examiner US. Cl. X.R. 

